The adhering of property to something else, by which the owner of one thing becomes possessed of a right to another; generally, gain of land by the washing up of sand or sail from the sea or a river, or by a gradual recession of the water from the usual watermark.

(b)

Gain to an heir or legatee, failure of a coheir to the same succession, or a co-legatee of the same thing, to take his share.